Hyperledger has been collecting some use cases, though not all are fleshed out. You are correct that not every problem is suited to being solved by use of a blockchain.
Blockchain should be considered when you have a process that involves multiple parties, that don't necessarily trust one another, or a process that is subject to fraud and abuse. Some processes that can be improved by sharing data might be suitable for blockchain, however, within a single org, a distributed database can also suffice.